Portulaca oleracea L. is an annual plant, is also referred to as Oh-hang-cho, Chang-myeong-chae, Ma-chi-chae, or the like, often grows along roadsides, and in vegetable patches and unoccupied lands, and is an edible thickleaf plant. Portulaca oleracea L. is distributed around the world, and in Korea, in the summer, a soft portion thereof is blanched in boiling water and dried, and, in the winter, the dried plant is seasoned as a side dish. As for a folk remedy, Portulaca oleracea L. has been used as an antidote, a preservative, an antiscorbutic agent, an anticonvulsant, a diuretic, an anthelmintic agent, or a skin sedative, and additionally, its muscle relaxation activity, and antibacterial, anticancer, and antioxidative effects are also known. Portulaca oleracea L. consists of L-noradrenalin, dopamine, dopa and various organic acids, aminoacids, and terphene glycoside (portuloside A), and high concentration of omega-3 fatty acid, such as a linolenic acid.
Perilla is an annual herbaceous plant that is produced in many Asian countries including Korea, China, and Japan, and contains various useful components. Due to the inclusion of useful components, perilla is used as a pharmaceutical crop, an oilseed crop, and a leaf vegetable. That is, the seed of perilla is rich in an alpha-linolenic acid, which is an omega-3 fatty acid, and due to the alpha-linolenic acid, perilla has various body modulation functions: for example, brain activities are promoted, synthesis of eicosanoid that causes adult disease, such as high blood pressure or allergic disease, is suppressed, learning abilities are improved, and lifespans are prolonged. Thus, the seed is, as the whole seed, used in a perilla tea or confections, and an oil extracted from the seed is used for edible food, pharmaceutical, and industrial purposes.
Methods for creating highly added values by using perilla and Portulaca oleracea L. having such components and efficacies have not yet been sufficiently developed. Accordingly, a technology that utilizes a great amount of perilla and Portulaca oleracea L. needs to be developed.
An omega-3 fatty acid is an unsaturated fatty acid included in an external blue colored fish, and examples thereof are EPA, DHA, a linolenic acid, etc. The omega-3 fatty acid is not synthesized in vivo and thus needed to be obtained from foods. DHA is a major component of brain cells and occupies about 10% of a brain cell membrane lipid, and aids information transfer energy metabolism, which is necessarily required for brain cell activities, protein synthesis, memorization, and learning abilities, and prevents brain disorders. Also, DHA suppresses platelet aggregation and extends a blood coagulation time to prevent generation of blood clots, and thus, DHA is effective for the prevention of circulatory disease, such as stroke, heart disease, arteriosclerosis, or high blood pressure. Also, it is reported that DHA lowers the levels of blood cholesterol and neutral fat to prevent blood clots and strengthen blood vessels, thereby causing smooth blood circulation and preventing circulatory disease, such as high blood pressure, or arteriosclerosis. It is also reported that omega-3 decreases the level of low-density lipoproteins (LDL), which is a bad cholesterol, and increases the level of high-density lipoproteins (HDL), which is a good cholesterol.
When typical extraction and purification methods are used, extraction amounts of enriched materials are very high. However, the enriched materials may also include other unnecessary components. Also, the methods require use of various organic solvents that are harmful for the human body, and thus, the residual solvent may highly likely remain in the target extract. Also, the amounts of organic solvents used in the methods are high, thereby increasing the production costs and causing environmental pollutions.
A supercritical fluid extraction technology is a technology using a fluid at a critical temperature or higher and at a critical pressure or higher, and is getting attention as a new environmentally friendly clean technology that replaces conventional processes in the extraction and purification related fields including purification of medical products, food process, and petroleum chemical materials. In particular, recently, due to increasing energy source prices, environmental problems of conventional separation processes, and a high demand for special-purpose novel materials, which cannot be produced by using gas or liquid processes, industrialized countries are focused on the development of a novel process fluid technology using a supercritical fluid as a process fluid for the last 30 years, as an alternative of a conventional process using gas or liquid. As a result, the process that uses a supercritical fluid as a process fluid is rapidly introduced to all the industries, including fine chemistry, energy, environmental, and novel materials industries and replaces various conventional separation technologies.
Initially, the supercritical fluid technology for the extraction and purification of natural materials was limitedly applied to spices, cosmetic products, non-polar materials, such as fat, low-price foods, or flavoring materials. However, recently, due to the development of various phenomenological characteristics and additional technology related to this technology, the supercritical fluid technology can be applied to extract and purify polarity, small, or high-price natural medical products. There are many candidates for a supercritical fluid, and among supercritical fluids, carbon dioxide is the most often used. Carbon dioxide exists unlimitedly in the nature, and also, a great amount thereof is produced in iron-manufacturing or petroleum chemistry industries. Also, carbon dioxide is colorless and odorless, and is not harmful to the human body and is a chemically very stable material.
Also, compared to other fluids, carbon dioxide has low critical temperature (31.1° C.) and low critical pressure (7.4 MPa) and thus, is easily controlled to comply with a supercritical condition. Thus, use of carbon dioxide is environmentally friendly and enables efficient use of energy. Additionally, when this technology is used in separate and purify natural bioactive materials, problems of human body toxicity caused by an organic solvent remaining in the final products, high costs, environmental pollution due to wasted solvents, degeneration of a target component, and low extraction selectivity, which occurs when a typical process is conducted, may be addressed or compensated for.
The supercritical fluid technology using carbon dioxide has never been used to extract a bioactive component of Portulaca oleracea L., in particular, an omega-3 fatty acid component.
Korean Patent Registration No. 0558382 discloses a method of producing a ginkgo leaf extract by using a supercritical fluid extraction method. However, this method is different from a method of producing an omega fatty acid-containing extract from a plant by supercritical carbon dioxide extraction.